1. Field of the Invention
The present invention is related to grounding of a connector of a card reader, and especially to an improved connector of which a main body is integrally made by injection molding purely of plastic, and of which a grounding electric circuit is connected to a USB connecting port to effectively avoid external static-electricity interference against the electric elements of the card reader.
2. Description of the Prior Art
As shown in FIG. 1 which is a perspective schematic view of the internal structure of a conventional card reader, it is shown that the whole card reader 10 includes a circuit board 12 in a housing 11 as a principal unit. The circuit board 12 is provided with a USB connecting port to be connected with a circuit of a set of electric equipment (not shown) to form circuit connecting of the card reader 10 with the electric equipment, and to supply power for operation of the card reader 10.
The circuit board 12 is provided at least with a connector 14 for insertion of a memory card, the entire card reader 10 also is provided on the circuit board 12 with electric elements such as an integrated circuit 15 to control operation of the card reader 10, and further to form circuit connection of the memory card with the electric equipment.
And more, an inserting portion of each connector 14 of a card reader 10 generally is allocated on the front side of the housing 11 in favor of inserting and drawing out for changing a memory card, and the front side of the housing 11 is provided with an opening for passing of the memory card therethrough, thereby the memory card can get in the card reader 10 to surely insert in and connect with the connector 14. However, the housing 11 with the opening for passing therethrough the memory card will also form an area losing shielding for the housing 11, and is subjected to direct incidence of external static electricity onto the circuit board 12 in the housing 11 through the opening, this will induce damage against the internal electric elements such as the integrated circuit 15, and even on the contrary make destruction against the memory card by electro-static discharging (ESD) of the internal electric elements such as the integrated circuit 15. Therefore, the connector applied on a portable device such as the card reader 10 especially needs increased ability of anti-ESD.
Conventional anti-ESD techniques used on such a card reader 10 mainly have the connector 14 covered thereover with a metallic shielding layer 20, and the metallic shielding layer 20 further is connected with passive elements such as electric induction and protecting diodes etc. against static discharging to improve the ability of anti-ESD. However, the main body of the connector 14 mainly is made by injection molding of plastic, while the metallic shielding layer 20 is made of metal by punching process, hence the entire connector 14 has to be completed by respectively finishing productions of semi-finished articles including the main body and the metallic shielding layer 20 by using different techniques and equipment, which semi-finished articles then are assembled to connect the metallic shielding layer 20 with the main body of the connector 14; in this way, not only the cost of production of the connector is increased, but the yield of production of such connectors still can not be effectively increased.
Particularly, with a limited space of the card reader 10, for the sake of improving the function of anti-ESD, additional passive elements such as electric induction and protecting diodes etc. against static discharging must be allocated on the extremely small circuit board 12, these elements not only occupy much space on the circuit board 12, but also lower the flexibility of designing of related circuits.